Arteriovenous Malformation (AVM) is generally named as “brain vascular tangle” among the general public and in everyday usage. In fact, AVM is exactly what it sounds like; a vascular tangle formed by the abnormal interconnection of arteries and veins in the brain.
The arterial blood vessels carry oxygen-rich blood from the heart to the brain cells. Venous blood vessels carry oxygen-depleted blood back to the lungs and heart. Connection of arterial and venous blood vessels disrupts this vital process.
Arteriovenous malformations may develop not only in the brain, but also anywhere in the body. Since they are most common in the brain and spinal cord although they are rare, brain vascular tangles are thought of when AVMs are mentioned. The exact cause of brain vascular tangles is unknown; they may be congenital or develop later.
People with brain AVMs may rarely complain of headaches or seizures. However, AVM is usually detected during a brain scan for another health problem. In some patients, it is detected after rupture of blood vessels and brain hemorrhage.
How is a brain vascular tangle recognized?
A brain vascular tangle may not cause any symptoms unless the AVM ruptures and causes bleeding. In about half of all cases, the first symptom comes with a brain hemorrhage. In the others, the following symptoms may be seen:
- Having seizures,
- Severe headaches that do not alleviate,
- Muscle weakness or paralysis in one part of the body,
- Numbness or loss of sensation,
- Loss of vision,
- Difficulty in speaking,
- Blurred consciousness
Symptoms caused by brain AVM may occur at any age. However, they are most commonly seen between the ages of 10 and 40.
If you have seizures, severe headaches or any of the other symptoms, seek medical advice immediately. Click here to learn the symptoms related to a brain hemorrhage.
What is AVM?
In normal functioning, arterial blood vessels send oxygen-rich blood from the heart to the brain cells. The arterial blood vessels branch off into smaller and smaller branches and form a network that ends in capillaries. In the capillaries, blood flow is slow, and oxygen is slowly delivered to the brain cells.
Oxygen-depleted blood passes through small blood vessels into the venous blood vessels. It then returns to the heart and lungs for more oxygen. On the other hand, in case of AVM, the arterial and venous blood vessels are deprived of this supporting network of smaller blood vessels and capillaries. Bypassing the surrounding tissues, the blood passes directly from arterial to venous blood vessel.
Potential Risks
Vascular tangles in the brain may lead to the following risky conditions:
Brain hemorrhage
AVM may cause thinning or weakening of the walls of the affected vessel due to excessive pressure. This may lead to rupture of the vessel and brain hemorrhage. AVM hemorrhage is an important cause of brain hemorrhage in children and young adults
Oxygen deprivation of the brain
In the brain vascular tangle, blood bypasses the capillaries and flows directly from arterial to venous blood vessel. Capillaries slow down the blood flow and increase oxygenation of brain cells. However, due to AVM, the blood that is flowing into the venous blood vessel without using the capillaries cannot adequately oxygenate the brain tissues. Brain cells that cannot get enough oxygen weaken or may die.
Brain Aneurysm
The vessel walls may become thinner or weakened because of AVM. Over time, the weakened vessel wall may rise outwards. This condition, which is also known as bubble formation in the brain, causes the vessel’s becoming prone to rupture.
